<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
    <style>
      .outer {
        width: 200px;
        height: 200px;
        background-color: red;
        overflow-y: scroll;
      }
      .inner {
        width: 200px;
        height: 600px;
        background-color: aqua;
      }
    </style>
  </head>
  <body>
    <div class="outer" id="outer">
      <div class="inner"></div>
    </div>
  </body>
  <script>
    document.getElementById('outer').addEventListener('scroll', function (e) {
      console.log(e.srcElement.scrollTop);
    });
  </script>
</html>
